The present invention relates in general to mining machines, and more particularly to longwall mining machines of the type having a housing structure extending along one side of the course of travel of the machine, together with a side arm on the mining machine which extends through a slot in the housing structure for supporting and guiding power cables and a liquid supply conduit for the machine.
A mining machine of the aforesaid type is shown, for example, in U.S. Pat. No. 4,025,118. By reference to that patent, it will be seen that it discloses a housing structure which extends along one side of the course of travel of a long-wall mining machine, the housing structure having an internal space which accommodates at least a portion of an extended length of power cable for the mining machine. The housing assembly includes a face plate having a longitudinal slot extending along the length of the housing and facing toward the mining machine. A side arm on the mining machine extends through the slot and supports a length of the power cable extending through the slot in the face plate, this latter length of cable being connected to power supply terminals within the mining machine itself.
Power supply cables of the type described above, particularly when they are used without any cable chain, are subjected to heavy wear even when they are disposed inside the aforesaid housing structure. This wear arises from movement of the cable which is dragged along inside the housing assembly as the mining machine moves back and forth and because of the very narrow radius of curvature of the cable loop, the height of the loop being determined by either the diameter of the roller of a cable trolley or, in the absence thereof, by the limited height inside the housing assembly. In this respect, the curved portion of the cable loop, and particularly that portion in the entry zone where the cable enters the machine, suffer severe deformation of the cable sheathing with the eventual result of damage due to the strong pull exerted in this zone and because of twisting of the cable. As a result, when cable wear becomes excessive, either the cable has to be shortened by an amount equal to the length of the worn part or the complete cable has to be replaced. Work of this type underground is labor intensive and time consuming since the cable extends into the interior of the machine body and into an airtight chamber where the various cable strands are connected to terminals. As a consequence, any shortening or replacement of the cable caused by wear requires assembly work on or in the mining machine, an operation which is dangerous since it must be carried out within the range of machine movement.